Clearly you guys are using custard with too much artificial colouring
Well, as Dowie said, context is key.
A monkey mascot for a zoo? Fine.
A monkey mascot for a company specialising in Afro-Caribbean ready meals? Might want to rethink that one!
If you started calling someone with an unusually long neck "giraffe boy/girl", then it wouldn't be too surprising for them to take offense (if they were particularly sensitive about it), in fact to be honest, insinuating that someone is "animal like" is generally insulting, e.g.:
"dog" - ugly
"pig" - fat/disgusting
"<female dog>" - horrible person (usually female), see also "cow"
"<slang name for cat>" - coward
"(loan,card, etc.) shark" - cutthroat and generally nasty
"ape" - even ignoring the racial links, this still suggests someone who is generally a bit thick and tends to solve their problems "physically"
"whale" - fat
"snake" - devious/backstabbing